Although I have books of prose and prayer, catechisms, bibles and lives of saints, for example, I would say that my upstairs library focus, where I spend most time, contains a lions share of art pictorial books (mostly religious), art history and art instruction.
Some books address general topics and others review and detail highly specialized areas. They aren't for show, I actually read and mark them up
(to the chagrin of some).
Below: Snapshots of my assortment (but not all).
Click to view.